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LEVITATION TRANSPORTATION SYSTEM
This application is based on Japanese Patent Application No. 11-244174 (1999) filed Aug. 31, 1999, the content of 5 which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a superconductive magnetic levitation transportation system, more specifically to a superconductive magnetic levitation transportation system which performs short to long distance transportation of cargoes such as mails, foods, or the like with saved energy 15 and without causing pollution by using superconductive magnetic levitation for utilizing potential energy as a drive source of a transportation vehicle.
2. Description of the Related Art
Heretofore, methods for transporting mails or foods per- 20 form the transportation in the air, on the roads or rails utilizing airplanes, ships, automobiles, railways, and the like.
In such conventional transportation methods, since transportation is performed in the air, on the roads or rails while 25 bearing large amounts of loss, there are required large amounts of fuel costs and labor costs, as well as substantial production costs of the transportation vehicles, furthermore, there are substantial effects on the environmental degradation. 30
Since prior art methods for transporting a cargo by airplanes, ships, or automobiles utilize petroleum as drive energy, they considerably tend to have adverse effects on the environment such as emission of hazardous substances by
exhaust gases, acceleration of the global warming phenomenon by generation of C02, air pollution by abrasion dust of tires. Further, for railways, a great importance is attached to environmental pollution due to nuclear power generation and thermal power generation for producing the electric energy. Still further, each of these transportation methods is very large in air drag loss for traveling in the air and frictional loss, and dissipates a large amount of petroleum which is concerned about its storage amount in the future.
SUMMARY OF THE INVENTION 45
With the aim of solving the above-described prior art problems, it is an object of the present invention to provide an energy-saving superconductive magnetic levitation transportation system which uses high-temperature superconduc- 50 tive magnetic levitation, which is extremely small in bearing loss, for non-contact levitation of a transportation vehicle, making a transportation passage in which the transportation vehicle travels to a vacuum or a reduced pressure atmosphere in order to remarkably reduce air drag loss, to reduce 55 the drag during traveling to nearly zero, thereby supplying almost of the traveling drive force by the potential energy.
A yet further object of the present invention is to provide an energy-saving superconductive magnetic levitation transportation system which enables large-capacity transporta- go tion by connecting or providing a plurality of small-capacity transportation vehicles.
To accomplish the above objects, in a superconductive magnetic levitation transportation system according to the present invention, a transportation vehicle having a trans- 65 portation cabin containing transportation cargoes is noncontactingly levitated by utilizing the pinning effect which is
one of superconduction phenomena, traveled on a rail provided with permanent magnets or electromagnets in a traveling direction disposed in a vacuum transportation passage provided with a level difference between a start location and a destination location, and stopped at the destination location by absorbing traveling kinetic energy with potential energy when, approaching the destination location.
Further, for loading and unloading the transportation cargoes and performing other works, the start location and the destination location are provided with vacuum doors capable of closing a transportation pipe end (stop location of the transportation vehicle), and inside of which has a structure capable of being opened to the atmosphere and made to a vacuum. Still further, potential energy corresponding to the loss generated during traveling can be recovered by carrying the transportation vehicle to a high position utilizing an elevator and the like.
According to an aspect of the present invention, there is provided a superconductive magnetic levitation transportation system, comprising:
a transportation vehicle provided with a transportation cabin loading a transportation cargo, a first magnetic levitation member including a superconductive member, and a first coupling coil; a magnetic levitation guide, having a second magnetic levitation member including a magnet opposing to the first magnetic levitation member and a second coupling coil magnetically coupled with the first coupling coil, for levitating the transportation vehicle; and a transportation passage surrounding the transportation vehicle and the magnetic levitation guide in a vacuum or a reduced pressure atmosphere and disposed to have a level difference; wherein the transportation vehicle is levitated on the magnetic levitation guide by the superconductive pinning effect of the first magnetic levitation member of the transportation vehicle and the second magnetic levitation member of the magnetic levitation guide so that the transportation vehicle is traveled by potential energy according to the disposition of the transportation passage, and the transportation vehicle is stopped driving, held or positioned by the first coupling coil of the transportation vehicle and the second coupling coil of the magnetic levitation guide. Here, the transportation vehicle preferably comprises a cold accumulator disposed in close contact with the superconductive member and a refrigerator or a coolant for cooling the cold accumulator.
The magnet may be a plurality of permanent magnets disposed along the magnetic levitation guide in a traveling direction with the same magnetic polarities.
Further, the magnet may be a plurality of electromagnets disposed along the magnetic levitation guide in the traveling direction.
Still further, the superconductive member is preferably a high-temperature superconductor having a strong pinning force (high critical current density), for example, an yttrium type oxide superconductor (YBa2Cu30;c) or a samarium type oxide superconductor (SmBa2Cu30;l;).
Yet further, the transportation vehicle may comprise the first magnetic levitation member and the first coupling coil disposed on one side with respect to the levitating direction and further a third magnetic levitation member and a third coupling coil disposed on the other side, and the magnetic levitation guide may comprise the second magnetic levitation member and the second coupling coil opposing to the
first magnetic levitation member and the first coupling coil of the transportation vehicle, and a fourth magnetic levitation member and a fourth coupling coil opposing to the third magnetic levitation member and the third coupling coil of the transportation vehicle. 5
Yet further, the transportation vehicle may further comprise a fifth magnetic levitation member and a fifth coupling coil on a side to which a centrifugal force is applied where the transportation passage is bent, the magnetic levitation guide may further comprise a sixth magnetic levitation 10 member opposing the fifth magnetic levitation member of the transportation vehicle.
Yet further, the transportation vehicle preferably has connection parts having a superconductor at one end with respect to the traveling direction and a magnet at the other 15 end, and a plurality of the transportation vehicles may be connected by the connection parts.
Yet further, the transportation passage preferably further has at opposite ends a start area and an arrival area partitioned by vacuum doors. 20
Yet further, there may be provided a second magnetic levitation guide disposed to be connected or branched to the magnetic levitation guide such that potential energy of an arrival area of the second magnetic levitation guide is different from that of the magnetic levitation guide. 25
As described above, with the present invention, a largecapacity transportation can be possible by using hightemperature superconductive magnetic levitation in the bearings of the transportation vehicle to achieve high efficiency with remarkable reduction of bearing loss, and by connect- 30 ing a plurality of small-capacity transportation vehicles.
According to the present invention, by achieving a highefficiency and high-capacity superconductive magnetic levitation transportation system, since external driving power is almost unnecessary and there is almost no environmental 35 pollution, the transportation system can greatly contribute to energy saving and solution of environmental problem.
Further, according to the present invention, it is possible to increase the natural frequency of each of the transportation vehicles and, since the kinetic energy of each transpor- 40 tation vehicle is not so large, when a malfunction occurs, energy can be dispersed and distributed, thereby minimizing effects on other system or peripheral apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS 45
FIGS. lAand IB are schematic construction diagrams of a superconductive magnetic levitation transportation system according to the present invention;
FIG. 2 is a schematic cross-section of the superconductive magnetic levitation transportation system according to the present invention;
FIG. 3 is a diagram for explaining a magnetic levitation guide provided with a coupling coil;
FIGS. 4A-^C are structural diagrams in a transportation 55 passage for other embodiments of a transportation vehicle and a magnetic levitation guide;
FIGS. 5A and 5B are diagrams showing the structure of a connection part for connecting respective transportation vehicles. 60
DETAILED DESCRIPTION OF THE
FIG. 1A shows a schematic construction diagram of a superconductive magnetic levitation transportation system 65 according to the present invention. The superconductive magnetic levitation transportation system of the present
invention can be installed, for example, on the ground, underground, in the sea or a lake, as well as on side or under walls of highways.
In FIG. 1A, the superconductive magnetic levitation transportation system comprises a single or a plurality of transportation vehicles 1, a magnetic levitation guide 2 provided with permanent magnets or electromagnets, and a transportation passage 3. At opposite ends of the transportation passage 3, a start area 4 and an arrival area 5 are provided. Further, the start area 4 has first and second vacuum doors 4a and 4b, and the arrival area 5 has first and second vacuum doors 5a and 5b, respectively.
The transportation vehicle 1, in a state that the first vacuum door 4a on the transportation passage 3 side is closed, and the second vacuum door 4b on the carry-in or carry-out side is open, is guided to the start area 4, thereafter, the second vacuum door 4b is closed, and inside of the start area 4 is evacuated. Next, the first vacuum door 4a is open, the transportation vehicle 1 is guided into the transportation passage 3. The transportation vehicle 1 is levitating or floating non-contactingly with low frictional resistance. Superconductive magnetic levitation holds the transportation vehicle 1 at a stable position utilizing mainly a binding force by the pinning effect of a superconductor.
The transportation vehicle 1 having mass m is accelerated to a high speed in a descending part by potential energy as a level difference on the magnetic levitation guide 2 in the transportation passage from the start area disposed at the highest position in the system, travels at a constant speed in a halfway flat d part, ascends in the vicinity of a destination location to store kinetic energy of the transportation vehicle as potential energy, decreases in speed and stops. At the arrival area 5, the second vacuum door 5b is closed and the first vacuum door 5a on the transportation passage 3 side is open, and the inside is in a vacuum state. When the transportation vehicle 1 arrives at the arrival area 5, the first vacuum door 5a is closed to make the inside of the arrival area 5 same state as the external atmosphere, thereafter, the second vacuum door 5b is opened, and carry-out or carry-in of the transported cargo can be performed. Further, as necessary, the transportation vehicle 1 is guided to a predetermined height by an elevator, transportation means or the like, where the potential energy lost in the outward way is recovered, which is used in the return way (not shown). Also in the return way, a start area and an arrival area are provided with a level difference same as in the outward way.
The transportation passage 3 further may comprise a branch part 7, whereby enabling transportation to an arrival area 6 at a B point. In this case, braking is possible by means of coupling coils 22 of the transportation vehicle 1 and the magnetic levitation guide 2 or an appropriate braking means provided at the arrival area 6.
FIG. IB shows a modified construction diagram of the transportation passage. As shown in FIG. IB, since a transportation passages 3' and a second magnetic levitation guide 2' are very small in traveling loss even if there are high and low positions repeatedly, kinetic energy is converted to potential energy during traveling towards a high position and the speed decreases, however, stored potential energy increases the speed in a descending part, so that there is almost no effect unless there is too large positional difference. In short, if the level difference is set such that potential energy by a height difference between the start area 4 and the arrival area 5 is greater than potential energy corresponding to total loss in the transportation passage 3, some level differences in the course of the transportation passage 3 would cause no problem.
In such a system, for a single transportation vehicle 1, a traveling speed of the transportation vehicle on a distance d of a flat straight passage and a time from the start position to the destination position are calculated as follows. That is, referring to FIG. 1, a distance (height) h of falling at a 5 constant acceleration a in a time t is;
the acceleration a is represented from a gradient a and gravitational acceleration g;
a speed v after a time of t second is;
From these formulae, as an example, how long of time in minute it takes in traveling on a straight line of a distance d=100 km is calculated in the case where a=5°, h=200 m. 2o
First, a time required from the inclined part to the straight part is from
a=9.8xsin 5°=0.854 m/s2 and x=200/tan 5°=2286 m t=
Therefore, the speed v attained in the straight part is
v=V(2x0.854x2286)=62.5 m/s=225 km/h.
From the above, the transportation vehicle 1 travels the 30 distance d of 100 km in 27 minutes.
When the transportation vehicle 1 has loss during traveling, lost energy is as follows. For example, since a thing of weight 1 ton at a height 200 m has potential energy of 2xl05 kgm, if loss due to air drag loss is assumed as zero 35 (because of traveling in vacuum) and loss due to vibration of the superconductive bearing is assumed as 10 W for a 1 ton vehicle, total loss generated during traveling is 10x(2x73.2+ 27x60)=17664 J. It is represented as 1.8 m in level difference. 40
Since the loss is generated in the superconductor, the vehicle must be cooled to its extent, however, cooling is unnecessary if cooling storage capacity of the transportation vehicle is large.
Yet further, the loss generated during traveling decreases 45 the speed of the vehicle. Since kinetic energy e of a 1 ton vehicle traveling at a speed of 225 km/h is
v=V(2x(1962000-17664)=62.36 m/s-224 km/h,
which is a speed decrease of about 1 km/h.
When the loss is 50W per ton, total loss during traveling 55 is 88320 J, which corresponds to a level difference of 9 m, and the speed is v=61 km/h=220 km/h, a decrease of 5 km/h.
FIG. 2 shows an example of detailed construction of the superconductive magnetic levitation transportation system according to the present invention. 60
The transportation vehicle 1 comprises a cargo cabin 11 disposed at the center of the vehicle, a refrigerator or a coolant supply source 12 disposed on opposite sides of the vehicle 1, a cold accumulator 13 disposed at the lower central part of the vehicle, a first coupling coil 14 disposed 65 at lower both sides of the vehicle, and a first magnetic levitation member 15. The cargo cabin 11 is a space for
loading cargoes. The refrigerator or coolant supply source 12 is a mechanism for cooling the cold accumulator 13, in which an appropriate chemical or electric refrigerator or a coolant such as liquid nitrogen is used. Further, it is also possible to cool the cargoes by cooling the cargo cabin 11 with the refrigerator or coolant supply source 12. The cold accumulator 13 is disposed almost in close contact with a superconductor constituting the first magnetic levitation member 15 to cool down the member.
The first coupling coil 14 is made of a normal conductor wire or a superconductor wire, which is a magnetic coupling coil used for traveling control such as stop at the arrival positiomand emergency stop or driving during traveling. The first magnetic levitation member 15 is a plate-formed superconductor (especially a high-temperature superconductor) disposed below the cold accumulator 13 at the lower,center of the vehicle which, as will be described later, non-contactingly levitates the transportation vehicle 1 for moving it at a high speed on the magnetic levitation guide 2.
Here, as the superconductor used in the present invention, in view of effectively utilizing the pinning effect, is preferably a yttrium type oxide superconductor (YBa2Cu30;c) or a samarium type oxide superconductor (SmBa2Cu30;l.) at present, however, if a superconductor is developed which has a large critical current density, it may be used. Further, since the critical temperature is about 90K, the cooling temperature may be maintained at the liquid nitrogen temperature of 77K.
A stationary side magnetic levitation guide 2 comprises a second magnetic levitation member 21 at a position opposing the first magnetic levitation member 15, that is, at the central upper part of the guide 2 along the traveling passage, and a second coupling coil 22 at a position opposing the first coupling coil 14, that is, at the upper part of opposite sides of the guide 2 along the traveling passage. As the second magnetic levitation member 21, mainly a permanent magnet is used, and a plurality of magnets are disposed with the same polarities so as to obtain a uniform magnetic field distribution for preventing occurrence of traveling drag. The second coupling coil 22, made of a normal conductor wire or a superconductor wire as for the first coupling coil 14, is for traveling control and driving, which is controlled according to a control signal from an external control apparatus.
The stationary side magnetic levitation guide 2 is fixed into the transportation passage 3. Further, inside of the transportation passage 3 is in a vacuum state or a reduced pressure atmosphere to suppress air drag loss by high-speed traveling of the transportation vehicle 1 as possible and to suppress influx of heat as possible to the superconductive magnetic levitation portion of the transportation vehicle 1.
Here, as an example, a case will be described in which a superconductor is disposed on the transportation vehicle 1 side, and, on the other hand, a permanent magnet for levitation is disposed on the magnetic levitation guide 2 side. In this case, to decrease the temperature of the first magnetic levitation member 15 (superconductor) on the transportation vehicle 1 side below the critical temperature, using the refrigerator or the coolant supply source 12 disposed on the transportation vehicle 1, the cold accumulator 13 disposed around the superconductor is cooled and further the first magnetic levitation member 15 is cooled. In this cooling, for example, at the start area 4, in a state that the transportation vehicle 1 is floated by inserting a spacer between the magnetic levitation guide 2 and the transportation vehicle 1, the superconductor 15 is cooled below the critical temperature. By the above method, the superconductor 15 trans